Landing gear for articulated trailers allows the raising, lowering and support of the forward end of the trailer in the engagement and disengagement from the prime mover (alternatively known as the tractor or truck) and allows the trailer to be freestanding whilst not in transit. In most instances the trailer itself is decoupled from a prime mover and then re-coupled to either the same prime mover or another depending on the logistics appropriate to the use.
A typical scenario is where a trailer is delivered to a loading dock for loading or unloading. The trailer will typically be loaded up to twenty tons in weight, and in some instances up to twenty five tons, on one trailer. The prime mover positions the trailer in the loading dock. The operator will de-latch the kingpin from the turntable (alternatively known as the fifth wheel) and disconnect the service lines. The operator will then manually lower the legs of the landing gear. The operator will then raise the forward end of the trailer to clear the trailer king pin from the turntable of the prime mover. Once the trailer king pin is clear of the prime mover turntable the prime mover can be driven clear of the trailer to leave the trailer freestanding. The prime mover is then typically utilized elsewhere in a more productive role than being idle whilst the trailer is loaded or unloaded. The trailer will then be loaded or unloaded which may take a portion of an hour or it may take several days. Once the trailer is loaded or unloaded, a prime mover will then return to the trailer for the removal from the loading dock.
Under certain conditions of loading and unloading, there is a potential for trailer nose or tail diving. Seldom used or rusted landing gear may collapse under extreme weight conditions. When fork-trucks load or unload at the front of trailers, the trailer can become nose heavy and tip over. An unsupported spotted trailer can collapse with fork truck and diver inside, creating a hazardous situation. Trailer tip over caused by rusted or faulty landing gear can be very costly with injuries to employees, downtime, and loss of product.
Currently, devices known as “trailer jacks” or “trailer stands” are often used to act as a safety support under the front end of a trailer when it is being loaded or unloaded with the trailer resting on its support legs rather than on a tractor fifth wheel or converter dolly. Many of these known devices use mechanical means to adjust the height of the support which are exposed such as cranks and gears that must be ratcheted or cranked up and down. These known devices may fail due to corrosion and friction between gears causing wear. Such devices include the Bulter/Kelly Trailer Stand and T&S Models and the Roto Riser™ trailer stand from TMI Inc. Other devices use hydraulic or pneumatic means to adjust the height of the support. One such device is the AUTO-RISER™ trailer stand from TMI Inc. which uses a gas activated leveling system and a security locking pin. The AUTO-RISER™ trailer stand requires the operator to bend over or to squat down to insert and remove the security locking pin, the act of which may result in injury to the operator.